From: Jens Axboe <jens.axboe@oracle.com>
To: Eduard - Gabriel Munteanu <eduard.munteanu@linux360.ro>
Cc: Mathieu Desnoyers <compudj@krystal.dyndns.org>,
Tom Zanussi <tzanussi@gmail.com>,
penberg@cs.helsinki.fi, akpm@linux-foundation.org,
linux-kernel@vger.kernel.org, righi.andrea@gmail.com
Subject: Re: [PATCH 2/3] relay: Fix race condition which occurs when reading across CPUs.
Date: Mon, 16 Jun 2008 18:46:10 +0200 [thread overview]
Message-ID: <20080616164609.GM20851@kernel.dk> (raw)
In-Reply-To: <20080616162212.27a8c119@linux360.ro>
On Mon, Jun 16 2008, Eduard - Gabriel Munteanu wrote:
> On Mon, 16 Jun 2008 08:22:49 -0400
> Mathieu Desnoyers <compudj@krystal.dyndns.org> wrote:
>
> > Hi Eduard,
>
> Hi.
>
> > Two objections against this. First, taking a spinlock _is_ slow in SMP
> > because it involves synchronized atomic operations.
>
> In any case, if we use relay in a hot path, we are doing debugging, so
> a couple of atomic operations won't be a big problem. Along with
> setting affinity, this shouldn't be a problem.
Ehm no, that is a completely false claim. Relay speed does matter, a
great deal. We rely heavily on eg blktrace being as ligt weight as
possible to capture millions of events in a very short time frame
without impacting performance too much. Relay is NOT just for debugging.
So I completely agree with Mathieu here, and I'm not a big fan of the
proposed solution.
--
Jens Axboe
next prev parent reply other threads:[~2008-06-16 16:46 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-06-13 1:09 [PATCH 2/3] relay: Fix race condition which occurs when reading across CPUs Eduard - Gabriel Munteanu
2008-06-14 4:26 ` Tom Zanussi
2008-06-14 15:11 ` Eduard - Gabriel Munteanu
2008-06-14 16:16 ` Pekka Enberg
2008-06-16 5:38 ` Tom Zanussi
2008-06-16 6:19 ` Pekka Enberg
2008-06-17 4:52 ` Tom Zanussi
2008-06-16 12:22 ` Mathieu Desnoyers
2008-06-16 13:22 ` Eduard - Gabriel Munteanu
2008-06-16 16:46 ` Jens Axboe [this message]
2008-06-16 18:18 ` Pekka Enberg
2008-06-16 18:23 ` Mathieu Desnoyers
2008-06-16 18:28 ` Jens Axboe
2008-06-17 12:39 ` Eduard - Gabriel Munteanu
2008-06-17 12:49 ` Eduard - Gabriel Munteanu
2008-06-17 13:10 ` Mathieu Desnoyers
2008-06-17 13:35 ` Eduard - Gabriel Munteanu
2008-06-17 13:50 ` Mathieu Desnoyers
2008-06-17 14:55 ` Eduard - Gabriel Munteanu
2008-06-17 12:55 ` Mathieu Desnoyers
2008-06-17 13:21 ` Eduard - Gabriel Munteanu
-- strict thread matches above, loose matches on Subject: below --
2008-06-12 20:26 Eduard - Gabriel Munteanu
2008-06-12 22:58 ` Andrea Righi
2008-06-12 23:15 ` Eduard - Gabriel Munteanu
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